Abstraction and interpretation of pertinent research data from the medical and toxicological literature on issues that are to be dealt with in the Office of Health Hazard Assessment. Recent topics of concern were as follows: Co-oxidation of xenotoxic chemicals by prostaglandin synthetase, the nature of cytosolic receptors for steroids and other non-related chemicals, the abundance of multiple forms of cytochrome P-450 and their significance in metabolism of xenobiotics, virus - chemical interactions in relation to the development of cancer, the toxic effects of breakdown products of some nonpersistent pesticides, etc.